Photographic materials with removable antihalation layers

ABSTRACT

1. A PHOTOGRAPHIC MATERIAL COMPRISING A HYDROPHOBIC FILM SUPPORT, AT LEAST ONE LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER, AND AT THE SIDE OF THE SUPPORT OPPOSITE TO SAID LIGHT-SENSITIVE EMULSION LAYER OF LAYERS AN ANTIHALATION LAYER CONSISTING OF A DYE OR FINELY DIVIDED PIGMENT DISPERSED IN A WATER-INSOLUBLE, ALKALI-SOLUBLE POLYMER, CHARACTERIZED IN THAT BETWEEN SAID HYDROPHOBIC FILM SUPPORT AND SAID ANTHIHALATION LAYER AN INTERMEDIATE LAYER IS APPLIED, WHICH IS FORMED FROM A MIXTURE OF 1 TO 3 PARTS BY WEIGHT OF CELLULOSE DIACETATE OR TRIACETATE AND 3 TO 1 PARTS BY WEIGHT OF AB ALKALI-SOLUBLE POLYMER.

United States Patent 3,846,134 PHOTOGRAPHIC MATERIALS WITH REMOVABLE ANTIHALATION LAYERS August Jean Van Paesschen, Antwerp, and Joseph Antoine Herbots, Edegem, Belgium, assignors to Agfa-Gevaert N.V., Mortsel, Belgium No Drawing. Filed Oct. 19, 1971, Ser. No. 190,647 Claims priority, application Great Britain, Oct. 20, 1970, 49,791/ 70 The term of this patent subsequent to Apr. 10, 1990, has been disclaimed Int. Cl. G03c 1 84 US. Cl. 9684 R 4 Claims ABSTRACT OF THE DISCLOSURE In a photographic material comprising a hydrophobic film support carrying one or more light-sensitive silver halide emulsion layers there is applied to the side of the support opposite to the light-sensitive emulsion layer or layers an antihalation layer consisting of a dye or finely divided pigment dispersed in a water-insoluble, alkalisoluble copolymer. To facilitate the removal of the antihalation layer in the developer bath or during a separate rinsing with water when the photographic material before development is treated in a preliminary bath, there is applied between the hydrophobic film support and the antihalation layer an intermediate layer formed from a mixture of l to 3 parts by weight of a cellulose ester and 3 to 1 parts by weight of at least one alkali-soluble polymer.

This invention relates to photographic materials and particularly to photographic elements carrying light-sensitive silver halide emulsion layers.

The problem of reducing halation in sensitive photographic materials is Well known. Halation arises as a consequence of the reflection of light by the film support onto the light-sensitive coating or coatings. It is usually neutralized by applying to the side of the film support opposite to the emulsion layer or layers, a light-absorbing layer, which is generally called anti-halation layer. Such an antihalation layer may consist of a dye or pigment dispersed in natural or synthetic binder. There is either selected a dye or pigment that is decolourized during the processing of the photographic element, or a natural or synthetic binder that is soluble in a processing bath. Both alternatives may be combined also.

It has now been found that the removal of the antihalation layer in the developer bath or in water when a preliminary bath is used, is greatly facilitated when an intermediate layer of a well defined composition is applied between the hydrophobic film support and the antihalation layer.

According to the invention a photographic material is provided comprising a hydrophobic film support, at least one light-sensitive silver halide emulsion layer, and at the side of the support opposite to said light-sensitive emulsion layer or layers an antihalation layer consisting of a dye or finely divided pigment dispersed in a waterinsoluble alkali-soluble polymer, characterized in that between said hydrophobic film support and said antihalation layer an intermediate layer is applied which is formed from a mixture of 1 to 3 parts by weight of a cellulose ester and 3 to 1 parts by weight of at least one alkalisoluble polymer.

Since in the intermediate layer the cellulose ester itself is not alkali-soluble, it is only the alkali-soluble polymer that dissolves away, thus leaving a thin layer of cellulose ester on the hydrophobic film support.

Suitable alkali-soluble polymers for use in the intermediate layer are e.g.:

ice

partially or completely sulphonated polystyrene co(styrene/maleic acid) partially or completely nitrated co(styrene/maleic acid) co(vinyl acetate/maleic acid) (50:50 mole percent) co(vinyl acetate/crotonic acid) (94:6% by weight) co(styrene/acrylic acid) (70:30% by weight) co(styrene/methacrylic acid) (30:70% by weight) whereby these polymers and copolymers may be applied in their acid form or as alkali metal salts.

Suitable cellulose esters for use in admixture with the alkali-soluble polymers are cellulose triacetate and especially cellulose diacetate having an acetic acid content between 52% and 60% by weight.

When cellulose triacetate is used for the hydrophobic film support, the mixture of cellulose ester and alkalisoluble polymer can be applied directly to the support. In the case of other hydrophobic film supports, e.g. of polyesters, it may be necessary to apply to the film support a known subbing layer composition or to pretreat the hydrophobic film support in a known manner.

The antihalation layer itself is formed from a dye or finely divided pigment dispersed in a water-insoluble, alkali-soluble, polymer. The dyes used may belong to almost all known classes of dyes, but especially to the classes of triphenyl methane, oxonol, merocyanine, styryl neutrocyanine, pyrrolocyanine, and styryl dyes. If a pigment is used, carbon black is preferred though sometimes colloidal silver may also be used.

Suitable water-insoluble, alkali-soluble polymers used as binding agents in the antihalation layer are e.g.

co(styrene/acrylic acid) (70:30% by weight) co(methyl acrylate/ acrylic acid) (:20% by Weight) co(ethyl acrylate/methyl methacrylate/methacrylic acid) (35:35:30% by weight).

Here also the polymer in its acid form is insoluble in water, but dissolves readily in an alkaline photographic developer. Where a highly alkaline solution is used as a preliminary bath the polymer does not dissolve in this preliminary bath but can be easily eliminated by rinsing with Water before entering the first developing bath.

It may be very interesting to add to the coating composition of the antihalation layer a small amount of a Wetting agent such as an alkali metal alkyl sulphate of 8 to 20 carbon atoms, e.g.sodium octyl sulphate, sodium tetradecyl sulphate, sodium hexadecyl sulphate, ammoniurn octadecyl sulphate, and sodium oleyl sulphate.

When black inert pigments are used, their amount may vary within a fairly wide range. They should be present, however, in sufficient amounts so that their layers prevent visible light from penetrating therethrough. A particle diameter of 10 to nm. represents a practical range and 30 to 80 nm. a preferred range for the afore-said pigments.

The quantity of black inert pigment dispersed in the binder of the antihalation layer may vary from 1 to 2 parts by weight of pigment to 1 to 20 parts of binder.

The thickness of the antihalation layer is not critical, though generally thicknesses of 0.5 to 3a are used. The thickness of the layer and the amount of pigment should be chosen so that the resulting layer has an optical density of about 0.5 to 3.

In order to impart a low friction coefiicient and a complete water-repellence to the antihalation layer, the latter may be covered with a wax layer, e.g. a layer formed from a 0.1 to 0.2% by weight solution of carnauba-wax dissolved in perchloroethylene or another suitable organic solvent or solvents.

The intermediate layer and the antihalation coating composition may be applied to the hydrophobic film support by spray, brush, roller, doctor blade, air brush, or wiping techniques. Examples of hydrophobic film supports are films of cellulose triacetate, polyalkylene terephthalates, or polycarbonates.

The presence of the intermediate layer formed from cellulose ester and alkali-soluble polymer greatly facilitates the elimination of the antihalation layer in the developing bath or during a separate rinsing with water when a preliminary bath of high alkalinity is used. Where in some cases the elimination of the alkali-soluble antihalation layer could only be obtained by brushing, the presence of the intermediate layer makes it possible to eliminate the antihalation layer by simply rinsing with Water after treatment in a preliminary bath. When using antihalation layers comprising dyestutfs a much reduced rest colouration of the layer is observed after processing in the photographic baths.

The invention is illustrated by the following examples.

EXAMPLE 1 One side of a cellulose triacetate film having a thickness of 140 and comprising 15% by weight of triphenyl phosphate as plasticizer was covered at a ratio of 1 liter/ 40 in. with the following coating composition:

Ml. 10% by weight aqueous solution of the sodium salt of completely sulphonated polystyrene 30 Water 20 Methanol 250 Acetone 600 by weight solution in acetone of cellulose diacetate (56% by weight content of acetic acid) 100 After drying a clear layer was obtained, to which an antihalation layer was applied at a ratio of 1 liter/ 35 m. of a dispersion of 6.4 g. colloidal carbon, having a particle diameter of approximately 50 nm. in the following solution:

Ml. 26.5% by weight latex of co(ethyl acrylate/methyl methacrylate/methacrylic acid) (37:37:26% by weight) (prepared as described in Preparation 2 of United Kingdom Patent Application 7588/70 filed Feb. 17, 1970 by 'Gevaert-Agfa N.V.) 60 Ethanol 540 Isopropanol 400 The other side of the cellulose triacetate film support was coated with a known subbing layer and subsequently with a light-sensitive gelatin silver halide emulsion layer to form a photographic film material.

The photographic film was exposed image-wise and then led through a preliminary bath having the following composition:

Water "liter-.. 1 Sodium sulphite g 100 Sodium tetraborate g 20 Sodium hydroxide (up to pH 9.4).

4 EXAMPLE 2 A film of cellulose triacetate was coated at a ratio of 1 liter per 38 m? with a coating composition formed as follows:

10% aqueous solution of polystyrene sulphonic acid in which 71% of the styrene units had been sulphonated 50 Methanol 250 Acetone 350 Methylene chloride 310 5% solution in methylene chloride of cellulose triacetate 40 The dried layer was coated at a ratio of 1 liter/50 m. with an antihalation layer having the following composition:

The red dye corresponded to the formula:

nnwQ-o 00011 I coo- =NH:

The other side of the support was coated with the necessary light-sensitive layers to form a panchromatic photographic film material.

The antihalatiou layer was completely decolourized after a treatment for 2 minutes in the developing bath.

When the antihalation layer was applied to an intermediary layer without polystyrene sulphonic acid, a slightly red-brown restcolour remained after treatment in the developing bath.

EXAMPLE 3 A cellulose triacetate film comprising 15% by weight of triphenyl phosphate was coated at a ratio of 1 liter/ 35.5 m? with a layer having the following composition:

Co(styrene/maleic acid mono-sodium salt) (50:50

mole percent) g 3 Water ml 50 Methanol ml Acetone ml 700 5% by weight solution in acetone of cellulose diacetate (56% by weight of acetic acid) ml 100 The dried layer was covered at a ratio of 1 liter/50 m? with an antihalation layer having the following composition:

Green dye g 16 Violet dye g 9 Methanol ml 530 Ethanol ml 300 35% aqueous solution of hydrochloric acid ml 3 17.5% by weight solution in 70 volume parts of methanol and 30 volume parts of water of co- (methyl acrylate/acrylic acid) (67:33 mole percent) 1 The green dye corresponded to the formula:

COOH C00- JJOOH JJOOH The violet dye corresponded to the formula:

CH3 COOH -Q-eQ A70 OH CH;

The other side of the cellulose triacetate film support was coated with the necessary light-sensitive layers to form a panchromatic photographic film material.

The antihalation layer was fully decolourized after a treatment lasting 2 minutes in the developing bath. When the co(styrene/maleic acid monosodium salt) had been omitted in the intermediate layer a restcolour remained after processing.

EXAMPLE 4 A cellulose triacetate film support was coated at a ratio of 1 liter/3O m? with an intermediate layer having the following composition:

M1. by weight aqueous solution of the sodium salt of polystyrene sulphonic acid 75 Methanol 300 Acetone 575 5% by weight solution of cellulose diacetate (acetic acid content 56.5% by weight) in acetone 50 The dried layer thus formed was covered at a ratio of 1 litre/48 m. with an antihalation layer having the following composition:

Green dye g Magenta dye g 10 Co(styrene/acrylic acid) (70:30% by weight) g The magenta dye corresponded to the formula:

COOH

The other side of the support was coated with the necessary light-sensitive layers to form a panchromatic photographic film material.

The antihalation layer was completely decolourized after a treatment of 2 minutes in the developing bath. When the sodium salt of polystyrene sulphonic acid was omitted from the intermediate layer, a slightly violet colour remained after processing.

What we claim is:

1. A photographic material comprising a hydrophobic film support, at least one light-sensitive silver halide emulsion layer, and at the side of the support opposite to said light-sensitive emulsion layer or layers an antihalation layer consisting of a dye or finely divided pigment dispersed in a Water-insoluble, alkali-soluble polymer, characterized in that between said hydrophobic film support and said antihalation layer an intermediate layer is ap' plied, which is formed from a mixture of 1 to 3 parts by weight of cellulose diacetate or triacetate and 3 to 1 parts by weight of an alkali-soluble polymer.

2. A photographic material according to claim 1, characterized in that the intermediate layer is formed from a mixture of cellulose diacetate and the sodium salt of polystyrene sulphonic acid.

3. A photographic material according to claim 1, characterized in that the intermediate layer is formed from a mixture of cellulose diacetate and the sodium salt of co(styrene/maleic acid).

4. A photographic material according to claim 1, characterized in that the intermediate layer is formed from a mixture of cellulose diacetate and the sodium salt of co(vinylacetate/maleic acid).

References Cited UNITED STATES PATENTS 3,392,022 7/1968 Gandy et a]. 9684 3,514,291 5/1970 Vanpoecke et a1. 9687 3,433,638 3/1969 Ohi et a1. 9684 3,681,070 8/1972 Timmerman et al. 9687 A X 3,549,375 12/ 1970 Pechman 9684 RONALD H. SMITH, Primary Examiner US. Cl. X.R. 9687 A 

1. A PHOTOGRAPHIC MATERIAL COMPRISING A HYDROPHOBIC FILM SUPPORT, AT LEAST ONE LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER, AND AT THE SIDE OF THE SUPPORT OPPOSITE TO SAID LIGHT-SENSITIVE EMULSION LAYER OF LAYERS AN ANTIHALATION LAYER CONSISTING OF A DYE OR FINELY DIVIDED PIGMENT DISPERSED IN A WATER-INSOLUBLE, ALKALI-SOLUBLE POLYMER, CHARACTERIZED IN THAT BETWEEN SAID HYDROPHOBIC FILM SUPPORT AND SAID ANTHIHALATION LAYER AN INTERMEDIATE LAYER IS APPLIED, WHICH IS FORMED FROM A MIXTURE OF 1 TO 3 PARTS BY WEIGHT OF CELLULOSE DIACETATE OR TRIACETATE AND 3 TO 1 PARTS BY WEIGHT OF AB ALKALI-SOLUBLE POLYMER. 